Traditionally, telephone calls have been routed through the public switched telephone network ("PSTN") to interconnect subscribers wishing to speak with each other.
More recently, data networks have become commonly used to exchange data between interconnected computing devices. The best known example of such a network is the public internet.
In the presence of a data network and the PSTN, the desire to bridge traffic on one network to the other has been recognized, For example, the PSTN is often used to provide access to the data network.
Similarly, the use of a data network to carry voice traffic has also been recognized. Accordingly, computer applications that allow end-users to establish voice connections using a data network are known.
Additionally, the use of a data network to transparently carry calls between end-users on the PSTN is also known. This is often done to avoid toll charges associated with the PSTN.
Finally, the bridging of calls originating with a caller on the telephone network and an end-user at a data network has also been recognized. This form of bridging is often performed as a matter of convenience, and is often used when a telephone connection is not available to the end-user resulting, for example, from the end-user's use of the telephone line to establish a connection to the data network.
Devices used for this latter form of bridging are, for example, disclosed in PCT patent publication no. WO 97/20424. However, such bridging assumes that the data network offers sufficient capacity in order to carry call data. In reality, a data network, such as the public internet is often congested and therefore cannot adequately be used to carry voice traffic.
Accordingly, it would be desirable to provide a method and devices for bridging calls across networks that allow users to the flexibility of maintaining high quality call connections.